Dye and process of making same



Aug. 14, 1923. 1,464,802

G. s. BOHART DYE AND PROCESS OF MAKING SAME Original Filed May 9, 1917Else/hoy@ i0 fr'ifenress WITNESSES: INVENTOR Arronzunrs Patented Aug,lf3, i925,

UNITED STATES GEORGE S, BOHART, F WASHINGTON. DISTRICT H. VJHITTINGHAM'.TRUSTEE.

OF COLUMBlA, ASSIGNOR TO GEORGE OF BAL'IIIMIORITV4 MARYLAND.

DYE AND PROCESS OF MAKING SAIYIE.

Application filed May 5, R917. Scrul To uf/ cfm/n, if muy (formeren:

Be it known that l, Gnomi: Boimnr, u citizen ot' the United States,residing ut the city ol' ll'asliington, District of Columbia,

J hun, invented new und useful Improvement in D )cs und Processes ofMelting Sumo, ot which the following is :i spccilicution.

This invention reltiies to u method ot' nuiking uzulmio acid, which Ihure found to be a valuable dye Stull", and to d ycs and mcthods ofmilking the same from said dye stulf.

A hydrocyanio acid solution, rendered slightly alkaline with sodiumhydroxide or other alkali, at about room temperature (2()o undergoesspontaneous change in the course of Several, hours, resulting in 'theformation, in the solution, of :i brownish black, nppurentlj.' amorphousprecipitate, insoluble in Water and known uf; uz'ilmic unid, thechemical constitution of which hue not been satisfactorily established.

Azulniic acid is insoluble in water, hut ib is infulc soluhlc or-dispersed or rendered rol loiilul by thu addition to it oi' an alkalior the solution of :in alkali in Waiter, as for instance, e 515i'caustic soda solution, and I hure found that this solution of azulmicacid in water containing an alkali, has the so property of dyeing cottonand other fabrics a variety of brown and reddish colors, depending onthe concentration of the dye, which muy bc above or below a 1% solution.

lf previous to its solution in un alkaline liquid, iiznlinic ucid istreated `with iin oxitlizing agent such as concentrated sulphuiic acid,or :i mixture of concentrated sulphurio acid und nitric acid (HNOQ, thelicr treated will be dyed :i ,golden yellow.

As rizulrnic acid is not un article ot' ordinary commerce, one of the,Qtr-ps of my process is the production of uzulrnic :ii-irl on ucommercial Scale.

The drawing diagrainmatically illustrates un apparatus suitable for thatpuriosc.

Sie); I. Frm/uiting oai/,finie ufff? com mi" rcfal/y.

i have discovered :1 rhifup, simple and direct, way for the nuniufactureof :izulmio acid on a commercial scale h v the ifhlition of sulphuric orother acid capable of decomposing cyanide, to n solution of e, arel nidein Water (a 10% solution of sodium cyanide has been found, qhitepractical) the further use by commonly o llll, Renewed Yl'tnc 2, 153234y in exch ol [il llllllli'il ulioul llllli,

ifyiiniilc solution heini; sliulill un cipiivulent ol' sulpliuric unid.the proportion ol :it-lil used ol' tliut iinipiii'cd ro lilil'iuc ullryunic acid from the runidc. from the known chemicul clpiiiziluiuii' ililuucid and the cyanide) so iliiii iluiii-ill is neutralized und som@ oliin nu tolli-f iunidc rcinuioszis such. 'l`liu i\ri-.-:1i-:lindalusoilium cyanide for instuni-ci l'wrnlus lli` ulloiliue conditionnecessary lor iluI olionmnuous change from h i'tlrocviuniilo -i/,ulniii'ruiil. '1 he reacting su'oslunccg.-` either 'oy slow uddition of acid orby cooling :iililifiiully :ii-e not allowed to l'ise inteiiipcruliii'iulioi that of the room, suy 2l) degrees l'., :ind :ii-cykept :it a temperature culculutcd to iiii'ewnl; the excessive loss ofhydrocyunic uuid hy volutilizetion. Advantages olf ilus method are that,the reactions ure Jurrie-l lo completion in a single vessel, und thisvessel muy hc omistructerl of iron. sinfe :it no time il; u crofrosivesolution Condition i'rcalcil.

rlfhe uzulinic :reid formed (composition un` known) is lilteied and thenwashed l'rec ol the reaction solution with weiter The yield is S', orbef-ter of the theoretical, which latter is calculated to he the weightot hydrocyunic ucid entering the reaction. The excess metallic cynnideremaining in the reaction solution may be recovered for known processesfor such a recovery, euch as evaporation, selective crystulliz'ntion ofimpurities, etc.

Azulmic :iriil thus recovered is in the torin of il brownish black,apparently amorphous precipitate, and insoluble in Water.

,Siep 2: Prodi/omg flu: linfa-*The next. s tep in the process is turender the :izulniio acid Soluble, for which purpose some fairly Stronglalkaline `Qolution ie mcd, for instance u caustic soda solution.

This solution of rizulinir' :icid in miteicontaining :in alkali,constitutes :i commercial dye producing various shades of lirown,depending on the concentration or dilution ot' the. d vo solution.

,l/cp J: DLI/@ing Uw frr1r[n-'l`lic t'iihiic to he dyed is immersed inun :illi'uline solution ot' rizulrnii acid either llc-t or cold. :ind ullowed to remain five minutes more. or less, until the cloth isimpregnated. und satur'utcd with the solution. Mechanical inczins, asrnhliing und :irritating muy lie employed to husten the absorption oithe five :oliiiiulifulutui l 'acid' By this fixing process the color ismade more resistant to Washing and bleaching agents.

Treating with metallic salts.

I have found that the azulmic acid dye is still further and moreeffectively fixed by iinmersing the fabric in an acid solution of acopper salt, as for instance a 5% copper sulphate solution with 1%sulphuric acid. This. treatment with a copper salt may be an additionlstep after the' acid fixing bath, or the copper salt may be dissolvedin the acid bath, The copper solution renders the dye more sun-fast andresistant to laundry' treatment. Other heavy metallic salts have similareffects to the copper treatment, as a cobalt nitrate solution, forexample. Shades of color may be regulated by thisl treatment withmetallic sa ts in solution. The excess of fixing solution is washed outwith water.

Producing oxidized azul/mic acid.

I have discovered that by treatin" the azuhnic acid with concentratedsulp inric acid or sulphuric and nitric acid, or other oxidizing agents,and then Washing the oxidized azulmic acid free of the oxidizing arentwith water, a dye stufiis produced willich is insoluble in water, butwhich is `soluble or is rendered colloidal by treatment wit-li analkaline solution as a 5% sodium hydroxide solution for example. Thisoxidized azulniic acid dissolved in alkaline solution may be applied tofabrics exactly as described above in the use of azulinic acid, and isfixed with acids in an acid hath, as described. Metallic salts areeli'ective in further fixing the oxidized azulmic acid. Yellow or goldenshades of color are produced by the oxidized azulinic acid, varying withthe concentration of the alkaline dye solution` and also with the choiceot' methods of' fixing.

Having thus described my invention what 1 claim and desire to secure byLetters Patent is- 1. The method of making azulmic acid dye stuff whichcomprises adding to asolation of cyanide in Water slightly less than an`equivalent of an acid capable of decomposing the cyanide, theproportion of decomposing acid added being suflicient to cause theliberation of most of the hydrocyanic acid in the cyanide and yet leavein the solution suflicient metallic cyanide to furnish the alkalinecondition necessary for causing the hydrocyanic acid liberated to changetoA azulmic acid, and freeing the azulmic acid formed from the reactionsolution.

2. The method of making azulmic acid dye which comprises adding to asolution of cyanide in water slightly less than an equivalent of an acidcapable of decomposing the cyanide, the proportion of decomposiii acidadded being sufficient to cause the li eration of most of thehydrocyanic acid in the cyanide and yet leave in the solution suflicientmetallic cyanide to furnish the` alkaline condition necessary forcausing the hydrocyanic acid liberated to change to azulmitI acid,freeing the azulniic acid form from the reaction solution, anddissolving the azuhnic acid in an alkaline solution.

3. The method of making oxidized azulmie acid dye which comprisestreating azulmic acid with an oxidizing agent and dissolving theoxidized azulmic acid in an alkaline solution.

4. The method of making oxidized azulmic acid dye which comprisestreating azulmic acid with an oxidizing avent, washing out the oxidizingagent, and dissolving the oxidized azulmic acid in an alkaline solution.

A dye consisting of a solution of azulinic acid in water containing analkali.

G. A dye comprisin oxidized azulmic acid dissolved in an al alinesolution.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing w i tnesses.

GEORGE S. BOHART.

Witnesses JOHN H. Hamme, W. W. HEALEY;

